The prior art embraces containers having a substantially rigid outer wrapper fashioned from a diecut blank.
More exactly, the blank consists in a flat piece of wrapping material foldable along selectively placed crease lines and score lines that serve to mark out a succession of panels, and a number of flaps arranged in such a way as to overlap at predetermined fixing areas when the blank is folded to erect the container.
The method by which these flaps are joined together to erect the container generally involve applying a layer of adhesive to the aforementioned fixing areas, preferably a cold-setting glue, in such a way that when the flaps are paired together they will bond swiftly one to another.
While serviceable, the method in question is less effective when the flaps of the container, or indeed all parts of the container, are made of plastic, plasticized or metallized material.
In effect, such materials are impermeable and unable to retain conventional cold-setting glues, so that the flaps cannot be bonded together by this method.
In prior art manufacturing systems, this drawback is overcome by using hot melt adhesives, which when heated will also enable the aforementioned impermeable materials to be bonded.
Nonetheless, adhesives of this type come with a number of drawbacks and are generally disagreeable to end users.
Firstly, hot melt glues tend to give off unpleasant odours, even after curing, which can render the product unattractive and adversely affect its quality, especially in the case of containers holding cigarettes or fragrances.
Also, hot melt adhesives typically crystallize when cooled, sometimes becoming fragile and liable to fracture.